The present invention relates to one-way clutches for use in starters or speed change gears for automobiles, or the like and more particularly to a retainer for holding engagement members between inner and outer rings.
A conventional one-way clutch is shown in Figs. 5A and 5B. FIGS. 5A and 5B are a front view and a cross sectional view of the one-way clutch, respectively.
As shown in FIGS. 5A and 5B, the one-way clutch has a plurality of sprags 8 serving as engagement members, an inner retainer 5 for retaining radially inner portions of the sprags 8, an outer retainer 1 for retaining radially outer portions of the sprags, and an annular ribbon spring 6 for urging the sprags 8 in one direction. The inner retainer 5, the outer retainer 1 and the ribbon spring 6 have generally rectangular pockets spaced at regular intervals in the circumferential direction for receiving the sprags 8, respectively. The one-way clutch is interposed between an inner ring 9 and an outer ring 7 and transmits a rotating torque from the inner ring 9 to the outer ring 7 through the sprags 8 only when the inner ring 9 rotates in one direction relative to the outer ring 7.
FIG. 4A is a partially cut-away front view of the outer retainer 1 of the one-way clutch and FIG. 4B is a fragmentary side view of the outer retainer 1. As shown in these figures, the pockets 2 of the outer retainer 1 are formed in a cylindrical part of the outer retainer 1. The outer retainer has an outer flange 3 extending radially outwardly from an axial end of the cylindrical part.
In the outer retainer 1, two slits 10 are provided. The slits 10 are connected with pockets 2 respectively and pass through the flange 3 to the outside of the outer retainer 1 such that a portion having a shape generally like that of two side-by-side and connected to (referred to as "connected-T bar" below) 4 is formed. The connected-T bar 4 protrudes radially outwardly, so that the distance between the center of the flange 3 and a radially outer surface of a flange portion 3' of the connected-T bar 4 is larger than a radius of an inner surface of the outer ring 7 where the outer retainer 1 is fitted. By an elastic force of the connected-T bar 4 which occurs when the outer retainer 1 is placed in position inside the outer ring 7, the radially outer surface of the flange portion 3' of the connected-T bar 4 is pressed against the inner surface of the outer ring 7, whereby the outer retainer 1 is fixed to the outer ring 7.
In the above-described conventional one-way clutch, however, the distance from the center of the outer flange 3 to the radially outer surface of the flange portion 3' of the connected-T bar 4 is made larger than the radius of the inner surface of the outer ring 7. Therefore, when the outer retainer 1 is placed in the outer ring 7, as shown in FIG. 5B, a counterforce or reaction force of the force of the connected-T bar 4 pushing the outer ring 7 acts on the flange portion 3. Therefore, the outer retainer 1 is caused to be displaced by the counterforce from a position 1' shown by a dotted line toward the direction opposite to the connected-T bar and the outer retainer 7 is made eccentric from the outer ring 7. As a result, some pockets 2 of the outer retainer 1 on the opposite side from the connected-T bar 4 are displaced from their normal positions relative to the sprags and get located at radially outer wide portions of the sprags 8.
Accordingly, there is a problem that the circumferential clearance between those displaced pockets 2 located on the opposite side from the connected-T bar 4 and the sprags 8 received in those pockets 2 is reduced and that motions of those sprags 8 are suppressed more than necessary.
The conventional one-way clutch has a further problem that it takes a long time to process the slits 10 to produce the connected-T bar 4. This is because the slits 10 can be worked only by a grinder for the reason that portions of the flange 3 to be cut out are located only on one side in the diametrical direction and that press-cutting would cause a large imbalance of force.